Bursting his bubble

AMSTERDAM, Netherlands -- The remnants of lunch were on Wilco Conradi's rosy cheeks when the 2-year-old grabbed a large ice cream and ran back to the table.

"Let's see if this tastes OK," he said, climbing onto his mother's lap.

This outing at the zoo once was unthinkable for the Dutch boy, who lived his first months in a germ-proof plastic enclosure after being born with severe combined immunodeficiency, or SCID. The plastic enclosure protected Wilco from infections that would have killed him.

But the blond, blue-eyed boy underwent a new gene therapy technique that apparently cured his disease and allowed him to leave his plastic bubble. He needs no medication or special treatment and eats a regular diet.

"He can go to school, go on vacation, and live like any other child," said his father, Theo Conradi.

Inherited disease

Wilco is among four boys successfully treated for the inherited disease that occurs in about one of every 75,000 births. The disorder, which is carried by women but afflicts only boys, has plagued Wilco's family for generations.

The illness renders the immune system ineffective against microbes ordinarily harmless to people with normal resistance. The best-known victim was David, Houston's famous "bubble boy," who lived in a germ-proof plastic enclosure until his death at age 12 in 1984.

Many afflicted babies are saved by bone marrow transplants, but for the rest of their lives take monthly intravenous infusions of immune globulin, antibodies culled from donated blood.

Experimental treatment

Wilco was a baby when he received the experimental treatment at the Hopital Necker-Enfants Malades in Paris. After receiving a single injection of genetically modified stem cells, Wilco now has a normal immune system.

In April, the experimental procedure passed its first major test when Wilco got sick with chicken pox and recovered.

Similar gene therapy might be used to fight other inherited disorders, Wulffraat said, "but these children will have to be followed for a long time" to know the long-term results.

The day Wilco was born, his father took a blood sample to Wulffraat, fearing the boy had inherited the disease. The diagnosis was confirmed hours later and the next day Wilco was admitted to the hospital.

Wulffraat then introduced the family to Paris immunologist Dr. Alain Fischer.

The four boys treated in France lacked an essential protein due to a genetic mutation. As a result, they could not produce two types of infection-fighting immune cells and a third type did not work, leaving their bodies vulnerable to infection.

To reverse that gene defect, doctors drew bone marrow from the boys. They culled stem cells from the marrow and mixed them with a harmless virus that contained a gene that makes the missing protein.

After the virus infected the bone marrow cells, millions of each boy's cells were injected to give them healthy immune systems.

Wilco visits the hospital four times a year. He does not remember his groundbreaking treatment or his infancy in isolation.